Multi-helix antenna on inflatable satellite



June 29, 1965 M. G. CHATELAIN MULTI-HELIX ANTENNA 0N INFLATABLE SATELLITE Filed March 20, 1961 INVENTOR.

MAURICE G. CHATELAI N BY Fig. 2

United States Patent 3,192,529 MULTI-HELIX ANTENNA N INFLATABLE SATELLITE Maurice G. Chatelain, San Diego, Calif., assignor to The Ryan Aeronautical Co., San Diego, Calif. Filed Mar. 20, 1961, Ser. No. 97,064 3 Claims. (Cl. 343844) The present invention relates generally to antennas and more particularly to a multi-helix antenna.

Various types of antennas have been used in space vehicles to direct or reflect radio frequency signals to ground based receivers, both rigid antennas mounted on an instrumented package and inflated, reflector type antennas. In order to be efiective at great distances, the reflective antenna must be of considerable size, the most practical configuration being a spherical balloon with a metallized surface, since this structure is light and can be packed in a small space and inflated after being placed in orbit. A spherical reflector is, however, of low efficiency due to the scattering of most of the incident energy and absence of directivity. It is desirable to construct an antenna of minimum weight, suitable for launching as a satellite vehicle, having means for control of directivity and being capable of reflecting a considerable portion of the incident energy.

The primary object of this invention, therefore, is to provide an inflatable antenna having a plurality of substantially radially directed elements each being in the form :of a conical helix and being effective over a wide range of frequencies.

Another object of this invention is to provide a multihelix antenna having means for interconnecting various elements individually or in groups to obtain the required directivity and beamwidth.

A further object of this invention is to provide a multihelix antenna constructed as an inflatable body of thin flexible material in generally spherical form and incorporating the conical elements integrally therewith, the spherical body portion being metallized and forming a ground plane for the elements.

Finally, it is an object to provide a multi-helix antenna of the aforementioned character which is simple and convenient to construct and which will give generally eflicient and durable service.

With these and other objects definitely in view, this invention consists in the novel construction, combination and arrangement of elements and portions, as will be hereinafter fully described in the specification, particularly pointed out in the claims, and illustrated in the drawing which forms a material part of this disclosure, and in which:

FIGURE 1 is a side elevation view of the antenna; and

FIGURE 2 is an enlarged, fragmentary sectional view taken on the line 2-2 of FIGURE 1.

Similar characters of reference indicate similar or identical elements and portions throughout the specification and throughout the views of the drawing.

The antenna comprises a substantially spherical body of thin, flexible material, such as plastic 12. Extending radially from the body 10 are a plurality of truncated cones 14, also of thin, flexible material. The cones 14 are preferably integral with the body 10 to be inflated as a unit therewith, but could be made individually inflatable to avoid collapse of the entire antenna from puncture of one cone. Various means have been devised for inflating ballon structures in space and need not be discussed in detail.

On each cone 14 is a helical antenna element 16, which is a metallic strip painted, vacuum deposited, or otherwise applied to the surface of the cone. The entire outer surhas.

face of the body 10 also has a metallic coating 18, which serves as a ground plane for the elements 16. The cones 14 are arranged in a suitable geometric pattern, the number of cones depending on the size of the antenna, the specific function and the degree of directivity required.

Radio frequency energyintercepted by the antenna will be reflected by the helical elements 16, the total reflected energy being considerably more than that obtainable from a plain sphere and with more directivity. To provide control of directivity, the elements 16 may be connected to a switching unit 20, as indicated diagrammatically in FIGURE 2, the switching unit being of mechanical, electronic, or any other suitable type. By interconnecting two elements 16, through the switching unit 20, a signal can be received from one direction and re-transmitted or reflected in another specific direction to a predetermined received location. Thus communications can be established between widely separated locations for which radio communication is otherwise diflicult due to the curvature of the earth obstructing ground transmission. For more precise directivity, the elements 16 may be connected in groups to reduce beamwidth, the phenomenon being well known.

The arrangement and action of the switching unit 20 will depend on the number of antenna elements, the degree of directivity required and various other factors, the design of a suitable unit being a simple matter for those skilled in the art. The switching action can be according to a predetermined program or selectively controlled by command signals, according to requirements.

The helical elements 16 can be single, as illustrated, or multifilar for greater directivity, with constant or variable width conductors, the radial length of each cone determining the directive characteristics and the apex angle determining the frequency bandwidth. The antenna is suitable for use as a passive reflector or may be used actively with self-contained or attached transmission means.

The operation of this invention will be clearly comprehended from a consideration of the foregoing description of the mechanical details thereof, taken in connection with the drawing and the above recited objects. It will be obvious that all said objects are amply achieved by this invention.

It is understood that minor variation from the form of the invention disclosed herein may be made without departure from the spirit and scope of the invention, and that the specification and drawing are to be considered as merely illustrative rather than limiting.

I claim:

1. An antenna, comprising:

an inflatable, substantially spherical body of thin, flexible material;

a plurality of radially extending antenna elements mounted in spaced relation on said body;

each of said elements consisting of a conical portion integral and inflatable with said body and having a helical conductor thereon.

2. An antenna, comprising:

an inflatable substantially spherical body of thin, flexible material;

a plurality of radially extending antenna elements mounted in spaced relation on said body;

each of said elements consisting of a conical portion integral and inflatable with said body and having a helical conductor thereon; said body having a conductive surface and constituting a ground plane for said elements.

3. An antenna according to claim 2 and including switch means connected to said elements and operable to interconnect selected elements.

(References on following page) Patented June 29, 1965 r '5 References Cited by theExaminer UNITED STATES PATENTS Wohl 343895 X Adcock et a1. 343--895 X Seyfang 343872 X Dyson 343--895 Harris 343-895 Haas 343-705 X Wheeler 343--895 Riblet 343895 4 3,063,048 11/62 Lehan et a1 343-895 X 3,098,229 7/63 Rahb 343705 OTHER REFERENCES 5 Airborne Spiral Antennas Minimize Drag by Philip Klass; Aviation Week, issue of July 14, 1958, pages 75, 77, 79, 81, 82.

Electronic Industries, March 1961, page 7.

1O HERMAN KARL SAALBACH, Primary Examiner.

GEORGE'N. WESTBY, ELI LIEBERMAN, Examiners. 

2. AN ANTENNA, COMPRISING: AN INFLATABLE SUBSTANTIALLY SPHERICAL BODY OF THIN, FLEXIBLE MATERIAL; A PLURALITY OF RADIALLY EXTENDING ANTENNA ELEMENTS MOUNTED IN SPACED RELATION ON SAID BODY; EACH OF SAID ELEMENTS CONSISTING OF A CONICAL PORTION INTEGRAL AND INFLATABLE WITH SAID BODY AND HAVING A HELICAL CONDUCTOR THEREON; SAID BODY HAVING A CONDUCTIVE SURFACE AND CONSTITUTING A GROUND PLANE FOR SAID ELEMENTS. 